Toast pistachios: Take 1 cup of pistachios and put in a saucepan with the walnut oil. Warm the oil and nuts together, be careful not to boil. Sauté garlic in a little olive oil. Prepare orzo from package instructions. When orzo has been drained, mix enough of the pistachios/walnut oil mixture to coat the pasta. Add lemon juice to taste. Mix in sautéed garlic. Add grapes, and half the basil. Chill for several hours, or overnight. Before serving, add rest of basil, salt and pepper to taste, and the rest of the pistachios.